Scaling Reads medium
You updated `style.css` but users are still downloading the old version from the CDN. Purging the CDN is slow. What is the most reliable way to force an instant update?
- A Restart the web server.
- B Cache Busting: Rename the file to `style.v2.css` or append a query param `style.css?v=2`.
- C Wait 24 hours.
- D Ask users to clear their cache.
Answer: B. Cache Busting: Rename the file to `style.v2.css` or append a query param `style.css?v=2`.
Changing the URL treats the resource as a brand new object. The CDN (and browser) will always fetch the new URL immediately.
One system design question a day, with spaced repetition so the ones you miss come back.
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